fix(lua): don't remove first char of non-file stacktrace source (#37008)

runtime/doc/lua.txt

@@ -236,7 +236,7 @@ Note:
 
                                                          *lua-script-location*
 To get its own location, Lua scripts/modules can use |debug.getinfo()|: >
-    debug.getinfo(1, 'S').source:sub(2)
+    debug.getinfo(1, 'S').source:gsub('^@', '')
 <
 
 ==============================================================================

runtime/lua/vim/_editor.lua

@@ -1252,7 +1252,7 @@ local function traceback()
     if not info then
       break
     end
-    local msg = ('  %s:%s'):format(info.source:sub(2), info.currentline)
+    local msg = ('  %s:%s'):format(info.source:gsub('^@', ''), info.currentline)
     table.insert(backtrace, msg)
     level = level + 1
   end

runtime/lua/vim/loader.lua

@@ -492,7 +492,7 @@ function M._profile(opts)
 
   if opts and opts.loaders then
     for l, loader in pairs(loaders) do
-      local loc = debug.getinfo(loader, 'Sn').source:sub(2)
+      local loc = debug.getinfo(loader, 'Sn').source:gsub('^@', '')
       loaders[l] = track('loader ' .. l .. ': ' .. loc, loader)
     end
   end

src/gen/gen_vimdoc.lua

@@ -895,7 +895,7 @@ end
 
 --- @return string
 local function get_script_path()
-  local str = debug.getinfo(2, 'S').source:sub(2)
+  local str = debug.getinfo(2, 'S').source:gsub('^@', '')
   return str:match('(.*[/\\])') or './'
 end
 

test/functional/core/startup_spec.lua

@@ -1243,7 +1243,7 @@ describe('user config init', function()
           string.format(
             [[
           vim.g.exrc_file = "%s"
-          vim.g.exrc_path = debug.getinfo(1, 'S').source:sub(2)
+          vim.g.exrc_path = debug.getinfo(1, 'S').source:gsub('^@', '')
           vim.g.exrc_count = (vim.g.exrc_count or 0) + 1
         ]],
             exrc_path